The Ackley Building (511 Washington Ave) is one of the few remaining cast iron commercial facades in downtown St. Louis, built in 1876 for Pratt, Simmons, and Krausnick, wholesale jobbers. It features three bays with composite Corinthian columns and retains original upper-story windows. In 1898–1899, architects Weber & Groves joined it with the neighboring Bradford-Martin Building (1875) for Crawford's Department Store, also adding the complex's famous glass-domed entrance. From 1904 to 1913 the combined building served as the flagship of David May's May Company department store — at the time the largest retail operation in the U.S. — before May moved operations to the Railway Exchange Building. It is considered the third-oldest surviving structure on Washington Avenue.
